# Leetcode

**Repository Path**: beifeng_java/Leetcode

## Basic Information

- **Project Name**: Leetcode
- **Description**: Leetcode刷题路径，题解
- **Primary Language**: Unknown
- **License**: MulanPSL-2.0
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 1
- **Forks**: 0
- **Created**: 2023-03-14
- **Last Updated**: 2025-04-02

## Categories & Tags

**Categories**: Uncategorized

**Tags**: LeetCode

## README

# 说明 #

- **可以按照分类刷题**，如果该分类题目较多，**可以自己选择其中的10题左右**。
- 类上$后面的数字为LeetCode或者力扣的题号，可以在网站上直接搜索即可。

## 按分类 ##
- [数组](https://gitee.com/beifeng_java/Leetcode/tree/master/java/array)
- [哈希表](https://gitee.com/beifeng_java/Leetcode/tree/master/java/hashmap)
- [树](https://gitee.com/beifeng_java/Leetcode/tree/master/java/tree)
- [链表](https://gitee.com/beifeng_java/Leetcode/tree/master/java/linkedlist)
- [动态规划](https://gitee.com/beifeng_java/Leetcode/tree/master/java/dp)
- [字符串](https://gitee.com/beifeng_java/Leetcode/tree/master/java/string)
- [二分查找](https://gitee.com/beifeng_java/Leetcode/tree/master/java/binarysearch)
- [滑动窗口](https://gitee.com/beifeng_java/Leetcode/tree/master/java/slidingwindow)
- [位运算](https://gitee.com/beifeng_java/Leetcode/tree/master/java/bit)
- [深度优先遍历](https://gitee.com/beifeng_java/Leetcode/tree/master/java/dfs)
- [数据库](https://gitee.com/beifeng_java/Leetcode/tree/master/java/sql)
- [图](https://gitee.com/beifeng_java/Leetcode/tree/master/java/graph)
- [贪婪算法](https://gitee.com/beifeng_java/Leetcode/blob/master/java/greedy)
## 按题号 ##
- [1.Two Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%241_TwoSum.java)
- [2.Add Two Numbers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/$2_Add%20Two%20Numbers.java)
- [3.Longes Substring Without Repeating Characters](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%243_LongesSubstringWithoutRepeatingCharacters.java)
- [4.Median of Two Sorted Arrays](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%244_MedianOfTwoSortedArrays.java)
- [5.Longest Palindromic Substring](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/$5_LongestPalindromicSubstring.java)
- [7.Reverse Integer](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%247_ReverseInteger.java)
- [8.String to Integer](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%248_StringToInteger.java)
- [9.Palindrome Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%249_PalindromeNumber.java)
- [10.Regular Expression Matching](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2410_RegularExpressionMatching.java)
- [12.Integer to Roman](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2412_IntegerToRoman.java)
- [13.Roman to Integer](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2413_RomanToInteger.java)
- [14.Longest Common Prefix](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2414_LongestCommonPrefix.java)
- [15.3 Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2415_3Sum.java)
- [16.3Sum Closest](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2416_3SumClosest.java)
- [17.Letter Combinations of a Phone Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2417_LetterCombinationsOfAPhoneNumber.java)
- [18.4 Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2418_4Sum.java)
- [19.Remove Nth Node From End of List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2419_RemoveNthNodeFromEndofList.java)
- [20.Valid Parentheses](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2420_ValidParentheses.java)
- [21.Merge Two Sorted Lists](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2421_MergeTwoSortedLists.java)
- [22.Generate Parentheses](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2422_GenerateParentheses.java)
- [23.Merge K Sorted Lists](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2423_MergeKSortedLists.java)
- [24.Swap Nodes In Pairs](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2424_SwapNodesInPairs.java)
- [25.Reverse Nodes In K-Group](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2425_ReverseNodesInKGroup.java)
- [28.Implement strStr()](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2428_ImplementstrStr.java)
- [29.Divide Two Integers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%2429_DivideTwoIntegers.java)
- [32.Longest Valid Parentheses](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2432_LongestValidParentheses.java)
- [33.Searching Rotated Sorted Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2433_SearchinRotatedSortedArray.java)
- [34.Find First and Last Position of Elementin Sorted Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2434_FindFirstandLastPositionofElementinSortedArray.java)
- [35.Search Insert Position](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%2435_SearchInsertPosition.java)
- [36.Valid Sudoku](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%2436_ValidSudoku.java)
- [37.Sudoku Solver](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%2437_SudokuSolver.java)
- [38.Count and Say](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2438_CountAndSay.java)
- [46.Permutations](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2446_Permutations.java)
- [47.Permutations II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2447_PermutationsII.java)
- [49.Group Anagrams](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%2449_GroupAnagrams.java)
- [50.pow(x,n)](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%2450_pow.java)
- [51.N-Queens](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2451_N_Queens.java)
- [52.N-Queens II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2452_N_QueensII.java)
- [53.Maximum Subarray](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2453_MaximumSubarray.java)
- [54.Spiral Matrix](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2454_SpiralMatrix.java)
- [55.Jump Game](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2455_JumpGame.java)
- [56.Merge Intervals](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2456_MergeIntervals.java)
- [58.Length of Last Word](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2458_LengthOfLastWord.java)
- [60.Permutation Sequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2460_PermutationSequence.java)
- [61.Rotate List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2461_RotateList.java)
- [62.Unique Paths](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2462_UniquePaths.java)
- [63.Unique Paths II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2463_UniquePathsII.java)
- [64.Minimum Path Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2464_MinimumPathSum.java)
- [67.Add Binary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%2467_AddBinary.java)
- [69.Sqrt(x)](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%2469_Sqrtx.java)
- [70.Climbing Stairs](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2470_ClimbingStairs.java)
- [72.Edit Distance](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2472_EditDistance.java)
- [74.Search A 2D Matrix](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2474_SearchA2DMatrix.java)
- [77.Combinations](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2477_Combinations.java)
- [78.Subsets](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2478_Subsets.java)
- [79.Word Search](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2479_WordSearch.java)
- [81.Searchin Rotated Sorted Array II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%2481_SearchinRotatedSortedArrayII.java)
- [82.Remove Duplicates From Sorted List II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2482_RemoveDuplicatesFromSortedListII.java)
- [83.Remove Duplicates from Sorted List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2483_RemoveDuplicatesfromSortedList.java)
- [86.Partition List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2486_PartitionList.java)
- [89.Gray Code](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2489_GrayCode.java)
- [90.Subsets II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2490_SubsetsII.java)
- [91.Decode Ways](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2491_DecodeWays.java)
- [92.Reverse Linked List II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%2492_ReverseLinkedListII.java)
- [93.Restore IP Addresses](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%2493_RestoreIPAddresses.java)
- [94.Binary Tree Inorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%2494_BinaryTreeInorderTraversal.java)
- [95.Unique Binary Search Trees II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%2495_UniqueBinarySearchTreesII.java)
- [96.Unique Binary Search Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%2496_UniqueBinarySearchTrees.java)
- [98.Validate Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%2498_ValidateBinarySearchTree.java)
- [99.Recover Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%2499_RecoverBinarySearchTree.java)
- [100.Same Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24100_SameTree.java)
- [101.Symmetric Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/$101_SymmetricTree.java)
- [102.Binary Tree Level Order Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24102_BinaryTreeLevelOrderTraversal.java)
- [103.Binary Tree Zigzag Level Order Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24103_BinaryTreeZigzagLevelOrderTraversal.java)
- [104. Maximum Depth of Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24104_MaximumDepthOfBinaryTree.java)
- [105.Construct Binary Tree from Preorder and Inorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24105_ConstructBinaryTreefromPreorderandInorderTraversal.java)
- [106.Construct Binary Tree from Inorder and Postorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24106_ConstructBinaryTreefromInorderandPostorderTraversal.java)
- [107. Binary Tree Level Order Traversal II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24107_BinaryTreeLevelOrderTraversalII.java)
- [108. Convert Sorted Array to Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24108_ConvertSortedArrayToBinarySearchTree.java)
- [109.Convert Sorted List to Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24109_ConvertSortedListtoBinarySearchTree.java)
- [110.Balanced Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24110_BalancedBinaryTree.java)
- [111.Minimum Depth of Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24111_MinimumDepthofBinaryTree.java)
- [112.Path Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24112_PathSum.java)
- [113. Path Sum II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24113_PathSumII.java)
- [114.Flatten Binary Tree To Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24114_FlattenBinaryTreeToLinkedList.java)
- [116.Populating Next Right Pointers in Each Node](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24116_PopulatingNextRightPointersInEachNode.java)
- [117.Populating Next Right Pointers in Each Node II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24117_PopulatingNextRightPointersInEachNodeII.java)
- [120.Triangle](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24120_Triangle.java)
- [121.Best Time to Buy and Sell Stock](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24121_BestTimeToBuyAndSellStock.java)
- [122.Best Time to Buy and Sell Stock II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24122_BestTimeToBuyAndSellStockII.java)
- [123.Best Time to Buy and Sell Stock III](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24123_BestTimeToBuyAndSellStockIII.java)
- [124.Binary Tree Maximum Path Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/$124_BinaryTreeMaximumPathSum.java)
- [125.Valid Palindrome](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24125_ValidPalindrome.java)
- [129.Sum Root to Leaf Numbers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24129_SumRootToLeafNumbers.java)
- [130.Surrounded Regions](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24130_SurroundedRegions.java)
- [131.Palindrome Partitioning](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24131_PalindromePartitioning.java)
- [133.Clone Graph](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24133_CloneGraph.java)
- [136.Single Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24136_SingleNumber.java)
- [139.Word Break](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24139_WordBreak.java)
- [141.Linked List Cycle](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24141_LinkedListCycle.java)
- [142.Linked List Cycle II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24142_LinkedListCycleII.java)
- [143.Reorder List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24143_ReorderList.java)
- [144.Binary Tree Preorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24144_BinaryTreePreorderTraversal.java)
- [145. Binary Tree Postorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24145_BinaryTreePostorderTraversal.java)
- [147.Insertion Sort List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24147_InsertionSortList.java)
- [152.Maximum Product Subarray](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24152_MaximumProductSubarray.java)
- [153.Find Minimum in Rotated Sorted Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24153_FindMinimumInRotatedSortedArray.java)
- [154.Find Minimum in Rotated Sorted Array II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24154_FindMinimuminRotatedSortedArrayII.java)
- [156.Binary Tree Upside Down](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24156_BinaryTreeUpsideDown.java)
- [159. Longest Substring with At Most Two Distinct Characters](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24159_LongestSubstringWithAtMostTwoDistinctCharacters.java)
- [160.Intersection Of Two Linked Lists](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24160_IntersectionOfTwoLinkedLists.java)
- [162.Find Peak Element](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24162_FindPeakElement.java)
- [163.Missing Ranges](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/$163_MissingRanges.java)
- [167.TwoSum II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24167_2SumII.java)
- [170.TwoSum III](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24170_TwoSumIII.java)
- [173.Binary Search Tree Iterator](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24173_BinarySearchTreeIterator.java)
- [175.Combine Two Tables](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/175.%20Combine%20Two%20Tables.txt)
- [176.Second 20Highest Salary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/176.%20Second%20Highest%20Salary.txt)
- [177.Nth Highest Salary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/177.%20Nth%20Highest%20Salary.txt)
- [178.Rank Scores](https://gitee.com/beifeng_java/Leetcode/tree/master/java/sql)
- [180.Consecutive Numbers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/180.%20Consecutive%20Numbers.txt)
- [181.Employees Earning More Than Their Managers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/181.%20Employees%20Earning%20More%20Than%20Their%20Managers.txt)
- [182.Duplicate Emails](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/182.%20Duplicate%20Emails.txt)
- [183.Customers Who Never Order](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/183.%20Customers%20Who%20Never%20Order.txt)
- [184.Department Highest Salary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/184.%20Department%20Highest%20Salary.txt)
- [185.Department Top Three Salaries](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/185.%20Department%20Top%20Three%20Salaries.txt)
- [187.Repeated DNA Sequences](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24187_RepeatedDNASequences.java)
- [190.ReverseBits](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%24190_ReverseBits.java)
- [191.Number Of 1 Bits](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%24191_NumberOf1Bits.java)
- [196.Delete Duplicate Emails](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/196.%20Delete%20Duplicate%20Emails.txt)
- [197.Rising Temperature](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/197.%20Rising%20Temperature.txt)
- [198.House Robber](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24198_HouseRobber.java)
- [199.Binary Tree Right Side View](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24199_BinaryTreeRightSideView.java)
- [200.Number of Islands](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24200_NumberOfIslands.java)
- [202.Happy Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24202_HappyNumber.java)
- [203.Remove Linked List Elements](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24203_RemoveLinkedListElements.java)
- [204.Count Primes](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24204_CountPrimes.java)
- [205.Isomorphic Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24205_IsomorphicStrings.java)
- [206.Reverse Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24206_ReverseLinkedList.java)
- [207.Course Schedule](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24207_CourseSchedule.java)
- [209.Minimum Size Subarray Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24209_MinimumSizeSubarraySum.java)
- [210.Course Schedule II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24210_CourseScheduleII.java)
- [213.House Robber II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24213_HouseRobberII.java)
- [221.Maximal Square](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24221_MaximalSquare.java)
- [222.Count Complete Tree Nodes](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24225_VerifyPreorderSequenceInBinarySearchTree.java)
- [226.Invert Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24226_InvertBinaryTree.java)
- [230. Kth Smallest Element in a BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24230_KthSmallestElementInABST.java)
- [234.Palindrome Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24234_PalindromeLinkedList.java)
- [235.Lowest Common Ancestor of a Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24235_LowestCommonAncestorOfABinarySearchTree.java)
- [236.Lowest Common Ancestor of a Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24236_LowestCommonAncestorofaBinaryTree.java)
- [237.Delete Node In A LinkedList](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24237_DeleteNodeInALinkedList.java)
- [240.Search a 2D Matrix II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24240_SearchA2DMatrixII.java)
- [242.Valid Anagram](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24242_ValidAnagram.java)
- [244.Shortest Word Distance II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24244_ShortestWordDistanceII.java)
- [246.Strobo grammatic Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24246_StrobogrammaticNumber.java)
- [249.Group Shifted Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24249_GroupShiftedStrings.java)
- [250.Count Univalue Subtrees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24250_CountUnivalueSubtrees.java)
- [254.Factor Combinations](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24254_FactorCombinations.java)
- [255.Verify Preorder Sequence in Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24225_VerifyPreorderSequenceInBinarySearchTree.java)
- [256.Paint House](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24256_PaintHouse.java)
- [257.Binary Tree Paths](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24257_BinaryTreePaths.java)
- [261.Graph Valid Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24261_GraphValidTree.java)
- [264.Ugly Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24264_UglyNumber.java)
- [266.Palindrome Permutation](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24266_PalindromePermutation.java)
- [269.Alien Dictionary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24269_AlienDictionary.java)
- [270.Closest Binary Search Tree Value](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24270_ClosestBinarySearchTreeValue.java)
- [272.Closest Binary Search Tree Value II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24272_ClosestBinarySearchTreeValueII.java)
- [274.H-Index](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24274_H_Index.java)
- [275.H-Index II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24275_H_IndexII.java)
- [276.Paint Fence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24276_PaintFence.java)
- [277.Find The Celebrity](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24277_FindTheCelebrity.java)
- [278.First Bad Version](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24278_FirstBadVersion.java)
- [279.Perfect Squares](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24279_PerfectSquares.java)
- [285.Inorder Successor in BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24285_InorderSuccessorInBST.java)
- [287.FindTheDuplicateNumber](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24287_FindTheDuplicateNumber.java)
- [290.Word Pattern](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24290_WordPattern.java)
- [293.Flip Game](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24293_FilpGame.java)
- [294.Flip Game II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24294_FlipGameII.java)
- [297.Serialize and Deserialize Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24297_SerializeandDeserializeBinaryTree.java)
- [298.Binary Tree Longest Consecutive Sequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24298_BinaryTreeLongestConsecutiveSequence.java)
- [299.Bulls And Cows](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24299_BullsAndCows.java)
- [300.Longest Increasing Subsequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24300_LongestIncreasingSubsequence.java)
- [303.Range Sum Query - Immutable](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24303_RangeSumQueryImmutable.java)
- [304.Range Sum Query 2D - Immutable](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24304_RangeSumQuery2DImmutable.java)
- [306.Additive Number](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24306_AdditiveNumber.java)
- [309.Best Time to Buy and Sell Stock with Cooldown](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24309_BestTimeToBuyAndSellStockWithCooldown.java)
- [310.Minimum Height Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24310_MinimumHeightTrees.java)
- [311.Sparse Matrix Multiplication](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24311_SparseMatrixMultiplication.java)
- [312.Burst Balloons](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24312_BurstBalloons.java)
- [320.Generalized Abbreviation](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24320_GeneralizedAbbreviation.java)
- [322.Coin Change](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24322_CoinChange.java)
- [323.Number of Connected Components in an Undirected Graph](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24323_NumberOfConnectedComponentsInAnUndirectedGraph.java)
- [328.Odd Even Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24328_OddEvenLinkedList.java)
- [333.Largest BST Subtree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/$333_LargestBSTSubtree.java)
- [344.Reverse String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24344_ReverseString.java)
- [337.House Robber III](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24337_HouseRobberIII.java)
- [338.Counting Bits](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24338_CountingBits.java)
- [339.Nested List Weight Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24339_NestedListWeightSum.java)
- [343.Integer Break](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24343_IntegerBreak.java)
- [345.Reverse Vowels of a String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24345_ReverseVowelsOfAString.java)
- [347. Top K Frequent Elements](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24347_TopKFrequentElements.java)
- [349.Intersection of Two Arrays](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24349_IntersectionOfTwoArrays.java)
- [350.Intersection of Two Arrays II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24350_IntersectionofTwoArraysII.java)
- [357.Count Numbers with Unique Digits](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24357_CountNumbersWithUniqueDigits.java)
- [359.Logger Rate Limiter](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24359_LoggerRateLimiter.java)
- [361.Bomb Enemy](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24361_BombEnemy.java)
- [366.Find Leaves of Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24366_FindLeavesOfBinaryTree.java)
- [367.Valid Perfect Square](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24367_ValidPerfectSquare.java)
- [369.Plus One Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24369_PlusOneLinkedList.java)
- [374.Guess Number Higher or Lower](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24374_GuessNumberHigherOrLower.java)
- [377.Combination Sum IV](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24377_CombinationSumIV.java )
- [378.Kth Smallest Element In A Sorted Matrix](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24378_KthSmallestElementInASortedMatrix.java)
- [379.Design Phone Directory](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24379_DesignPhoneDirectory.java)
- [383.Ransom Note](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24383_RansomNote.java)
- [387.First Unique Character in a String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24387_FirstUniqueCharacterInAString.java)
- [389.Find The Difference](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24389_FindTheDifference.java)
- [392.Is Subsequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24392_IsSubsequence.java)
- [394.Decode String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/bit/%24394_DecodeString.java)
- [401.Binary Watch](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24401_BinaryWatch.java)
- [404.Sum of Left Leaves](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24404_SumOfLeftLeaves.java)
- [409.Longest Palindrome](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24409_LongestPalindrome.java)
- [413.Arithmetic Slices](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24413_ArithmeticSlices.java)
- [415.Add Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24415_AddStrings.java)
- [416.Partition Equal Subset Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24416_PartitionEqualSubsetSum.java)
- [426.Convert Binary Search Tree to Sorted Doubly Linked List](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24426_ConvertBinarySearchTreetoSortedDoublyLinkedList.java)
- [428.Serialize and Deserialize N-ary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24428_SerializeandDeserializeN_aryTree.java)
- [429.N-ary Tree Level Order Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24429_NaryTreeLevelOrderTraversal.java)
- [431.Encode N-ary Tree to Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24431_EncodeN_aryTreetoBinaryTree.java)
- [434.Number of Segments in a String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24434_NumberOfSegmentsInAString.java)
- [437.Path Sum III](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24437_PathSumIII.java)
- [441.Arranging Coins](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24441_ArrangingCoins.java)
- [445.Add Two Numbers II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24445_AddTwoNumbersII.java)
- [447.Number of Boomerangs](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24447_NumberofBoomerangs.java)
- [449.Serialize and Deserialize BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24449_SerializeAndDeserializeBST.java)
- [450.Delete Node in a BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/$450_DeleteNodeInABST.java)
- [451. Sort Characters By Frequency](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24451_SortCharactersByFrequency.java)
- [454.4Sum II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24454_4SumII.java)
- [459.Repeated Substring Pattern](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24459_RepeatedSubstringPattern.java)
- [463.Island Perimeter](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24463_IslandPerimeter.java)
- [474.Ones and Zeroes](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24474_OnesAndZeroes.java)
- [486.Predict the Winner](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24486_PredictTheWinner.java)
- [494.Target Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24494_TargetSum.java)
- [500.Keyboard Row](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24500_KeyboardRow.java)
- [501.Find Mode in Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24501_FindModeInBinarySearchTree.java)
- [508.Most Frequent Subtree Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24508_MostFrequentSubtreeSum.java)
- [510.Inorder Successor in BST II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24510_InorderSuccessorinBSTII.java)
- [511.Game Play Analysis I](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/511.%20Game%20Play%20Analysis%20I.txt)
- [512.Game Play Analysis II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/sql/512.%20Game%20Play%20Analysis%20II.txt)
- [513.Find Bottom Left Tree Value](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24513_FindBottomLeftTreeValue.java)
- [515.Find Largest Value in Each Tree Row](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24515_FindLargestValueInEachTreeRow.java)
- [516.Longest Palindromic Subsequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24516_LongestPalindromicSubsequence.java)
- [520.Detect Capital](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24520_DetectCapital.java)
- [521.Longest Uncommon Subsequence I ](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24521_LongestUncommonSubsequenceI.java)
- [526.Beautiful Arrangement](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24526_BeautifulArrangement.java)
- [528.Random Pick with Weight](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24528_RandomPickWithWeight.java)
- [530.Minimum Absolute Difference in BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24530_MinimumAbsoluteDifferenceInBST.java)
- [535.Encode and Decode TinyURL](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24535_EncodeandDecodeTinyURL.java)
- [536. Construct Binary Tree from String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24536_ConstructBinaryTreefromString.java)
- [537.Complex Number Multiplication](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24537_ComplexNumberMultiplication.java)
- [538.Convert BST to Greater Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24538_ConvertBSTtoGreaterTree.java)
- [541.Reverse String II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24541_ReverseStringII.java)
- [543.Diameter of Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24543_DiameterofBinaryTree.java)
- [547.Friend Circles](https://gitee.com/beifeng_java/Leetcode/blob/master/java/graph/%24547_FriendCircles.java)
- [549.Binary Tree Longest Consecutive Sequence II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24549_BinaryTreeLongestConsecutiveSequenceII.java)
- [551.Student Attendance Record I](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24551_StudentAttendanceRecordI.java)
- [554.Brick Wall](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/$554_BrickWall.java)
- [557.Reverse Words in a String III](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24557_ReverseWordsInAStringIII.java)
- [559.Maximum Depth of N-ary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24559_MaximumDepthofNaryTree.java)
- [560.Subarray Sum Equals K](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24560_SubarraySumEqualsK.java)
- [563.Binary Tree Tilt](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24563_BinaryTreeTilt.java)
- [572.Subtree of Another Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24572_SubtreeofAnotherTree.java)
- [575.Distribute Candies](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24575_DistributeCandies.java)
- [582.Kill Process](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24582_KillProcess.java)
- [589. N-ary Tree Preorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24589_NaryTreePreorderTraversal.java)
- [590. N-ary Tree Postorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/$590_NaryTreePostorderTraversal.java)
- [594.Longest Harmonious Subsequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24594_LongestHarmoniousSubsequence.java)
- [599.Minimum Index Sum of Two Lists](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24599_MinimumIndexSumofTwoLists.java)
- [606.Construct String from Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24606_ConstructStringfromBinaryTree.java)
- [609.Find Duplicate File in System](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24609_FindDuplicateFileinSystem.java)
- [617.Merge Two Binary Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24617_MergeTwoBinaryTrees.java)
- [623.Add One Row to Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24623_AddOneRowtoTree.java)
- [637.Average of Levels in Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24637_AverageofLevelsinBinaryTree.java)
- [638.Shopping Offers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24638_ShoppingOffers.java)
- [646.Maximum Length of Pair Chain](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24646_MaximumLengthOfPairChain.java)
- [647.Palindromic Substrings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24647_PalindromicSubstrings.java)
- [648.Word Replace](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24648_WordReplace.java)
- [650.2 Keys Keyboard](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24650_2KeysKeyboard.java)
- [651.4 Keys Keyboard](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24651_4KeysKeyboard.java)
- [652.Find Duplicate Subtrees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24652_FindDuplicateSubtrees.java)
- [653.Two Sum IV - Input is a BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24653_TwoSumIV_InputisaBST.java)
- [654.Maximum Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24654_MaximumBinaryTree.java)
- [655.Print Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24655_PrintBinaryTree.java)
- [657.Robot Return to Origin](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24657_RobotReturnToOrigin.java)
- [658.Find K Closest Elements](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24658_FindKClosestElements.java)
- [662.Maximum Width of Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24662_MaximumWidthofBinaryTree.java)
- [663.Equal Tree Partition](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24663_EqualTreePartition.java)
- [666.Path Sum IV](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24666_PathSumIV.java)
- [669.Trim a Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24669_TrimaBinarySearchTree.java)
- [670.Maximum Swap](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24670_MaximumSwap.java)
- [671.Second Minimum Node In a Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24671_SecondMinimumNodeInaBinaryTree.java)
- [676.Implement Magic Dictionary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24676_ImplementMagicDictionary.java)
- [680.Valid Palindrome II](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24680_ValidPalindromeII.java)
- [686.Repeated String Match](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24686_RepeatedStringMatch.java)
- [687.Longest Univalue Path](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24687_LongestUnivaluePath.java)
- [690.Employee Importance](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24690_EmployeeImportance.java)
- [692.Top K Frequent Words](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24692_TopKFrequentWords.java)
- [694.Number of Distinct Islands](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24694_NumberOfDistinctIslands.java)
- [696.Count Binary Substrings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24696_CountBinarySubstrings.java)
- [700. Search in a Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24700_SearchInABinarySearchTree.java)
- [701.Insert Into A Binary Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24701_InsertIntoABinarySearchTree.java)
- [702.Search in a Sorted Array of Unknown Size](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24702_SearchInASortedArrayOfUnknownSize.java)
- [704.Binary Search](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24704_BinarySearch.java)
- [705.Design Hash Set](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24705_DesignHashSet.java)
- [709.To Lower Case](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24709_ToLowerCase.java)
- [712.Minimum ASCII Delete Sum for Two Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24712_MinimumASCIIDeleteSumForTwoStrings.java)
- [714.Best Time to Buy and Sell Stock with Transaction Fee](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24714_BestTimeToBuyAndSellStockWithTransactionFee.java)
- [718.Maximum Length of Repeated Subarray](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24718_MaximumLengthOfRepeatedSubarray.java)
- [725.Split Linked List In Parts](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24725_SplitLinkedListInParts.java)
- [748.Shortest Completing Word](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24748_ShortestCompletingWord.java)
- [750.Number Of Corner Rectangles](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24750_NumberOfCornerRectangles.java)
- [771.Jewels And Stones](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24771_JewelsAndStones.java)
- [729.My Calendar I](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24729_MyCalendarI.java)
- [733.Flood Fill](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dfs/%24733_FloodFill.java)
- [734. Sentence Similarity](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24734_SentenceSimilarity.java)
- [739.Daily Temperatures](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24739_DailyTemperatures.java)
- [740.Delete and Earn](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24740_DeleteAndEarn.java)
- [744.Find Smallest Letter Greater Than Target](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24704_BinarySearch.java)
- [746.Min Cost Climbing Stairs](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24746_MinCostClimbingStairs.java)
- [760.Find Anagram Mappings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24760_FindAnagramMappings.java)
- [765.Couples Holding Hands](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24765_CouplesHoldingHands.java)
- [783.Minimum Distance Between BST Nodes](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24783_MinimumDistanceBetweenBSTNodes.java)
- [784.Letter Case Permutation](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24784_LetterCasePermutation.java)
- [788.Rotated Digits](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24788_RotatedDigits.java)
- [791.Custom Sort String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24791_CustomSortString.java)
- [800.Similar RGB Color](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24800_SimilarRGBColor.java)
- [804.Unique Morse Code Words](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24804_UniqueMorseCodeWords.java)
- [813.Largest Sum of Averages](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24813_LargestSumOfAverages.java)
- [814.Binary Tree Pruning](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24814_BinaryTreePruning.java)
- [817.Linked List Components](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24817_LinkedListComponents.java)
- [819.Most Common Word](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24819_MostCommonWord.java)
- [824.Goat Latin](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24824_GoatLatin.java)
- [825.Friends Of Appropriate Ages](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24825_FriendsOfAppropriateAges.java)
- [842.Split Array into Fibonacci Sequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%24842_SplitArrayIntoFibonacciSequence.java)
- [852.Peak Index in a Mountain Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24852_PeakIndexInAMountainArray.java)
- [859.Buddy Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24859_BuddyStrings.java)
- [860.Lemonade Change](https://gitee.com/beifeng_java/Leetcode/blob/master/java/greedy/%24860_LemonadeChange.java)
- [862.Shortest Subarray with Sum at Least K](https://gitee.com/beifeng_java/Leetcode/blob/master/java/slidingwindow/%24862_ShortestSubarraywithSumatLeastK.java)
- [872.Leaf-Similar Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24872_LeafSimilarTrees.java)
- [873.Length of Longest Fibonacci Subsequence](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24873_LengthOfLongestFibonacciSubsequence.java)
- [876.Middle Of The LinkedList](https://gitee.com/beifeng_java/Leetcode/blob/master/java/linkedlist/%24876_MiddleOfTheLinkedList.java)
- [877.Stone Game](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24877_StoneGame.java)
- [881.Subdomain Visit Count](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24881_SubdomainVisitCount.java)
- [884.Uncommon Words from Two Sentences](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24884_UncommonWordsFromTwoSentences.java)
- [889.Construct Binary Tree from Preorder and Postorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24889_ConstructBinaryTreefromPreorderandPostorderTraversal.java)
- [890.Find and Replace Pattern](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24890_FindAndReplacePattern.java)
- [893.Groups of Special-Equivalent Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24893_GroupsOfSpecialEquivalentStrings.java)
- [894.All Possible Full Binary Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24894_AllPossibleFullBinaryTrees.java)
- [897.Increasing Order Search Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24897_IncreasingOrderSearchTree.java)
- [900.RLEIterator](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24900_RLEIterator.java)
- [911.Online Election](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%24911_OnlineElection.java)
- [915.Partition Array into Disjoint Intervals](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24915_PartitionArrayintoDisjointIntervals.java)
- [917.Reverse Only Letters](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24917_ReverseOnlyLetters.java)
- [925.Long Pressed Name](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24925_LongPressedName.java)
- [926.Flip String To Monotone Increasing](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24926_FlipStringToMonotoneIncreasing.java)
- [929.Unique Email Addresses](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24929_UniqueEmailAddresses.java)
- [931.Minimum Falling Path Sum](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24931_MinimumFallingPathSum.java)
- [937.Reorder Log Files](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%24937_ReorderLogFiles.java)
- [938.Range Sum Of BST](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24938_RangeSumOfBST.java)
- [944.Delete Columns to Make Sorted](https://gitee.com/beifeng_java/Leetcode/blob/master/java/greedy/%24944_DeleteColumnsToMakeSorted.java)
- [945.Minimum Increment to Make Array Unique](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24945_MinimumIncrementtoMakeArrayUnique.java)
- [951.Flip Equivalent Binary Trees](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24951_FlipEquivalentBinaryTrees.java)
- [953.Verifying an Alien Dictionary](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24953_VerifyinganAlienDictionary.java)
- [958.Check Completeness of a Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24958_CheckCompletenessofaBinaryTree.java)
- [961. N-Repeated Element in Size 2N Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%24961_NRepeatedElementinSize2NArray.java)
- [962.Maximum Width Ramp](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%24962_MaximumWidthRamp.java)
- [965.Univalued Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24965_UnivaluedBinaryTree.java)
- [968.Binary Tree Cameras](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24968_BinaryTreeCameras.java)
- [979.Distribute Coins in Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24979_DistributeCoinsinBinaryTree.java)
- [983.Minimum Cost For Tickets](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%24983_MinimumCostForTickets.java)
- [987.Vertical Order Traversal of a Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24987_VerticalOrderTraversalofaBinaryTree.java)
- [988.Smallest String Starting From Leaf](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24988_SmallestStringStartingFromLeaf.java)
- [993.Cousins in Binary Tree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%24993_CousinsinBinaryTree.java)
- [1007.Minimum Domino Rotations For Equal Row](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%241007_MinimumDominoRotationsForEqualRow.java) 
- [1008.Construct Binary Search Tree from Preorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%241008_ConstructBinarySearchTreefromPreorderTraversal.java)
- [1011.Capacity To Ship Packages Within D Days](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%241011_CapacityToShipPackagesWithinDDays.java)
- [1014.Best Sightseeing Pair](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%241014_BestSightseeingPair.java)
- [1022.Sum of Root To Leaf Binary Numbers](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%241022_SumofRootToLeafBinaryNumbers.java)
- [1025.Divisor Game](https://gitee.com/beifeng_java/Leetcode/blob/master/java/dp/%241025_DivisorGame.java)
- [1026.Maximum Difference Between Node and Ancestor](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%241026_MaximumDifferenceBetweenNodeandAncestor.java)
- [1028.Recover a Tree From Preorder Traversal](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%241028_RecoveraTreeFromPreorderTraversal.java)
- [1029.Two City Scheduling](https://gitee.com/beifeng_java/Leetcode/blob/master/java/greedy/%241029_TwoCityScheduling.java)
- [1046.Last Stone Weight](https://gitee.com/beifeng_java/Leetcode/blob/master/java/greedy/%241046_LastStoneWeight.java)
- [1060.Missing Element in Sorted Array](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%241060_MissingElementInSortedArray.java)
- [1064.Fixed Point](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%241064_FixedPoint.java)
- [1071.Greatest Common Divisor of Strings](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%241071_GreatestCommonDivisorOfStrings.java)
- [1078.Occurrences After Bigram](https://gitee.com/beifeng_java/Leetcode/blob/master/java/hashmap/%241078_OccurrencesAfterBigram.java)
- [1079.Letter Tile Possibilities](https://gitee.com/beifeng_java/Leetcode/blob/master/java/backtracking/%241079_LetterTilePossibilities.java)
- [1099.Two Sum Less Than K](https://gitee.com/beifeng_java/Leetcode/blob/master/java/array/%241099_TwoSumLessThanK.java)
- [1119.Remove Vowels from a String](https://gitee.com/beifeng_java/Leetcode/blob/master/java/string/%241119_RemoveVowelsfromAString.java)
- [1120.Maximum Average Subtree](https://gitee.com/beifeng_java/Leetcode/blob/master/java/tree/%241120_MaximumAverageSubtree.java)
- [1198.Find Smallest Common Element In All Rows](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%241198_FindSmallestCommonElementInAllRows.java)
- [1351.Count Negative Numbers In A Sorted Matrix](https://gitee.com/beifeng_java/Leetcode/blob/master/java/binarysearch/%241351_CountNegativeNumbersInASortedMatrix.java)